Compressed gas cylinders are bulky and heavy, and despite the use of heavy steel in the cylinders, they are surprisingly fragile. If the dispensing valve on the gas cylinder is broken off by rough handling, the consequences can be quite dangerous.
Accordingly, large numbers of compressed gas cylinders may be transported by a special system such as is shown in U.S. Pat. No. 5,573,360, or by a commercial transport truck bed that is available from the Welding Company of America of Northlake, Ill., which may be used for safer gas cylinder transport.
Such truck beds are divided into a plurality of bays in which each bay receives a pallet, which is latched in position, while the gas cylinders present on the pallets are tightly secured by a surrounding chain or the like. Typically, a lift gate is positioned at the rear of the truck body which carries the truck bed, with the lift gate being arranged vertically when the truck is enroute, to serve as a partition that prevents articles from falling off the bed. Then, the lift gate can be pivoted into a horizontal position and lowered to receive free-standing gas cylinders or other cargo. A conventional mechanism is operated to lift the gate, to enable the material to be easily loaded onto the truck body. Then, for transport, the lift gate is rotated 90° from horizontal to vertical, to serve as a back partition that assures retention of the cargo. The pallets are loaded on the body from the sides. The pallet bottoms from the flat surface onto which free standing cylinders may be rolled between the pallets and lift gate.
In the past, various companies have attached lift gate mountings to a truck body by attachment of a mounting to a pair of tubes which are carried on each side of the rear end of the truck and to which the lift gate was attached. There has been a problem of strength issues with this particular design.
Also, typically, a fence is required at the front end of the truck body which carries the above-described truck bed. Because various customers have varying requirements for the height of the front fence, depending upon the size and nature of the gas cylinders and other factors, a number of different designs of truck bed must be manufactured, each having a front fence of differing height. Thus, manufacturers must maintain a larger inventory of the various, different designs, and the user, having only one design, may encounter difficulties if the need arises to put the system to a use where a different fence height would be more optimum.
Special truck bodies of the prior art include those without a solid bed, but instead provide a grid of longitudinally and laterally extending beams, having spaces between them. This is adequate for receiving pallets, loaded and unloaded, and results in weight reduction, reduced cost for the truck bed, and other advantages, with full or empty pallets generally always covering the open spaces in the truck bed.
However, more recently, gas cylinders on a pallet have been connected to a manifold, which is carried by the pallet, so that the gas cylinders and the pallet are all unloaded and left at the site of use. Without an empty pallet to fill it, truck bed spaces can remain open, which can create hazard. By this invention, a simple means for avoiding the danger of such open spaces is provided.
Also, by this invention a simple, inexpensive truck body is provided, which comprises a truck bed without permanent sidewalls and roof, but which, when desired, can provide enclosure to the product carried on the truck bed, without the expense which must be incurred to obtain a full, closed-in trailer with permanent sidewalls and roof, and which also permits side loading of the cargo.